When the timeseries_insert_mixed_schema_bucket.js and jstests/core/timeseries/timeseries_update_mixed_schema_bucket.js tests were initially introduced in SERVER-84531, the tests were marked with the requires_fcv_80 tag, as the initial approach was that `collMod` commands with `timeseriesBucketsMayHaveMixedSchemaData` could only be executed after an FCV upgrade due to introducing an incompatible oplog change.

With SERVER-91195 the approach pivoted to make the change backportable and SERVER-92812 allowed collMod commands with timeseriesBucketsMayHaveMixedSchemaData to run on FCVs lower than 8.0 again. However, the tests still maintain the tag.

Remove the unnecessary tag (1, 2) to increase test coverage on 8.0, for example on the fcv_upgrade_downgrade_*_jscore_passthrough suites.